Some look like brains, some like arrowheads, others like beads, propellers or puffs of cotton. Seeds have evolved many of these striking features to help them propagate in the wild. The beadlike seeds of the Ormosia tree (8) attract birds with their bright red color. Mistaking them for berries, birds pluck the seeds from fruit and excrete them over a wide territory. Seeds with wings (18, 19) waft on wind currents; some (12) are weighted at the bottom so they can plant themselves on the forest floor; others (5, 22) can extend their journey by floating down rivers or streams. The seeds shown here are just some of the 750 that botan­ists Fernando Cornejo and John Janovec of the Botanical Research Institute of Texas have recently catalogued from the Amazonian wilderness. They range in size from five millimeters (10), about the size of a lentil, to 100 mm (1), about the size of a doughnut. “Seeds are the root of plant diversity,” Janovec says. “They represent the genetic blueprint being carried forward.” Their field guide, Seeds of Amazonian Plants, published by Princeton University Press, will help scientists understand how forests regenerate, how plants disperse, and how the varied species of this tropical region evolve together as a single ecosystem.